Treatment of ferrous bearing metals



Patented F eb. 9, 1943 John C. Zimmer,

Roselle,

Hillside, and Arnold J. Morway. N. 1., asslsnors to Standard Oil Devel- V opment Company, a corporation of Delaware No Drawing.

Application December '3, 1937, Serial No. 177,928

1 Claim. (01. ns-esi This invention relates to improved extreme pressure rubbing surfaces. the improvement of ferrous gears or other ferrous bearing elements which are subjected to high I pressures as, for example, ferrous gears of the ghypoid or similar type.

.The invention especially relates to the improvement of rubbing surfaces secured by a chemical pre-treatment of the said surfaces.

The present invention is to be distinguished from the mere cleansing of metallic surfaces with acidpick materials or to the treatment of surface for It is'concemed with the prevention of secondary read-'- tions such as oxidation. The present invention secures-improved rubbing ferrous surfaces by treating said surfaces with acids of phosphorus and boron and the salts-thereof, thereby increasing and improving their load carrying capacity.

' It iswell known in the art. to improvethe load carrying capacity of rubbing surfaces, ar.

ticularly hy'poid gears, .by theme of so-called "extreme pressure lubricants. These extreme pressure lubricants are usually sulphurized or chlorinated mineral or vegetable oils in combination with lead soaps. These extreme pressure lubricants are helpful in improving the load carrying capacity of the rubbing surfaces but-still- I are not entirely satisfactory at relatively high pressures under certainoperating conditions.

These extreme pressure lubricants requlre'acti vation to form an extreme pressure which film is formed by the development of a high temperature associated with bearing seizure. It is also known to plate steel gears with copper or tin inorder to decrease wear and thus avoid failprocess has the inherent disadvantages that the ures by seizure of the bearing surfaces. This plating chips and cracks or wears ofl. rather read- 1h. In addition, particularly in the case with copper plated gears, the metal. seems to act as oxidation and thickening of.

an accelerator for the gear iubricant. V

The present invention secures improved load carrying capacity by preactivation of the gears or rubbing surfaces and thereafter permits the use of an ordinary lubricant which would otherwise be entirely unsatisfactory. The process of the present invention'may alsogbe used in oonjunc tion with extreme pressure lubricants in orderto further increase load carrying capacity and min, imiz ebearingseizure. I Y

The improved ferrous rubbing surfaces such as rotation is 600 R. P. M. Fortiming'the v tion of weights, 9. bell, is provided and so-arrangedas follows:

agent selected from the group consisting of acids of phosphorus, acids of boron and the salts there- 01. Preferred rubbing surfaces are secured .by treating the ferrous metal with a phosphate, phosphite, thiophosphate or thiophosphite, especially by treating with a phosphate in the presence of a small quantity of phosphoric acid. The

- temperature of the treating solution is preferably maintained at approximately the boiling point. The mono phosphate and di or tri phosphate containing some free phosphoric acid group are all satisfactory for this purpose, or any combination of these materials. It is preferred to use the sodium salt of the oxyacids of phosphorus or boron although other metallicsalts are equally satisfactory.

The marked improvement secured by this process is shown by the following data where specific examples serve to illustrate the invention. Steel rods were treated in the manner describedand then were tested on the Almen machine,

which lS'dBSCl'ibBd' in detail in "the National Petroleum News, November 16, 1932. The operation of this machine. can be briefly summarized The machine is portable and employs a [1-inch drill-rod Journal and fa' /2-inch split bushing made of ,S. A. E. 2315 cold-drawn steel. The joumal' is. polished and the bushing after splitting is ground onthebearing surface with a form grinding ,wheel. A clearance'of 0.007 inch is provided between the journal and thenormal diameter of the bushing. Pressure is applied to the bushing means of a hydraulic and mecha'nical loading The friction torque developed is indicated. through a second hydraulic" system byaBourdongage.

In conducting a test the oil container is first filled with oil to be tested (about 25 ml.) sube merging the test'JournaL- The machine is then started and run for 30 seconds at no load to in- 5 sure thorough lubrication of the journal and bushing. The load is then appliedjat the rate of 2 lb.'-every 10 seconds until seizure occurs or until- .30 1b; have beenappiied. Thespeed of applica- -a's, mu g at zit-se uin; intervals; 'Eiich 2-1.

-ing.

gears, bearings. cams, Journals, pistons, cylinders,

rings, races,-valve stems, and the'lika are secured by treating: the metalwith a chemical reweight producesapressureof. approximately 1,000 1 1b. er-sq. in; ofproiec edarea on the test bear- .The rod-tested,on the -Almenmachine w a unem oun e mae bnwmn Y 2 S. A. E. 20, carried three weights before seizure occured. This mineral lubricating oil was used as the lubricant in all the following examples.

Example 2 An acid aqueous solution having a concentration of approximately of dibasic sodium phosphate was heated to boiling and the steel rod immersed for approximately 15 minutes. This rod was then dried and tested in the manner described in the preceding example. The rod carried 14 weights on the Almen machine.

Example 4 An aqueous solution of 2% tribasic sodium phosphate was heated to boiling and the steel rod immersed in said solution for approximately 15 minutes. This rod was then dried and tested in the manner described above. The rod carried five weights.

Example 5 An aqueous solution of 2% tribasic sodium phosphate and /2% phosphoric acid was heated to a temperature of approximately 80 F. and the steel rod immersed in said solution for approximately 15 minutes. This rod, after being dried, carried weights when tested on the Almen machine.

Emample 6 Procedure in accordance with the preceding example except that said solution was heated to boiling and the steel rod immersed for minutes. The rod, when tested on the Almen machine, carried 13 weights.

Example 7 An aqueous solution containing approximately 5% boric acid was heated to boiling and the steel rod immersed in said solution for about 30 minutes. The rod, upon being dried and tested on the Almen machine, carried 11 weights.

Example 8 An aqueous solution containing 2% boric acid nd V270 phosphoric acid was heated to boilin and the steel rod immersed in the solution for about 30 minutes. This rod, upon being dried and tested on the Almen machine, carried 14 weights.

1 Example 9 The operating conditions may be varied over wide limits. The treating operation may be carried out under pressure or vacuum although it is preferred to treat at atmospheric pressure. The temperature of the treatingbath may be as high as 300 F. although the preferred range is from about F. to the boiling point of the bath. It is preferred to maintain a temperature a few degrees below the boiling point of the respective baths. The time of treatment is less than about one hour, preferably a time of treatment from 15 minutes to 30 minutes. The concentration of inorganic material is maintained below about 20%. Concentrations from /z% to 10% are preferred.

The invention is not to be limited by any theory of operation but only by the following claim in which it is desired to claim 'all'rroveity in so far as the prior art permits.

We claim:

A process of preparing a ferrous metalbearin surface for use with a mineral lubricating oil comprising chemically treating said surface with an aqueous solution or dibasic sodium phosphate which will react therewith to form a coating of iron phosphate thereon.

JOHN C. ZIMMER. ARNOLD J. MORWAY. 

